Identifying and evaluating field indicators of urogenital schistosomiasis-related morbidity in preschool-aged children

Abstract

Background: Several studies have been conducted quantifying the impact of schistosome infections on health and development in school-aged children. In contrast, relatively little is known about morbidity levels in preschool-aged children (≤ 5 years) who have been neglected in terms of schistosome research and control. The aim of this study was to compare the utility of available point-of-care (POC) morbidity diagnostic tools in preschool versus primary school-aged children (6-10 years) and determine markers which can be used in the field to identify and quantify Schistosoma haematobium-related morbidity.

Methods/principal findings: A comparative cross-sectional study was conducted to evaluate the performance of currently available POC morbidity diagnostic tools on Zimbabwean children aged 1-5 years (n=104) and 6-10 years (n=194). Morbidity was determined using the POC diagnostics questionnaire-based reporting of haematuria and dysuria, clinical examination, urinalysis by dipsticks, and urine albumin-to-creatinine ratio (UACR). Attributable fractions were used to quantify the proportion of morbidity attributable to S. haematobium infection. Based on results of attributable fractions, UACR was identified as the most reliable tool for detecting schistosome-related morbidity, followed by dipsticks, visual urine inspection, questionnaires, and lastly clinical examination. The results of urine dipstick attributes showed that proteinuria and microhaematuria accounted for most differences between schistosome egg-positive and negative children (T=-50.1; p<0.001). These observations were consistent in preschool vs. primary school-aged children.

Conclusions/significance: Preschool-aged children in endemic areas can be effectively screened for schistosome-related morbidity using the same currently available diagnostic tools applicable to older children. UACR for detecting albuminuria is recommended as the best choice for rapid assessment of morbidity attributed to S. haematobium infection in children in the field. The use of dipstick microhaematuria and proteinuria as additional indicators of schistosome-related morbidity would improve the estimation of disease burden in young children.

Fig 1. Flowchart indicating number of children enrolled in the study and excluded from the final analysis.

Fig 2. Non-metric multidimensional scaling (NMDS) ordination in 2-dimensional configurations by sex, age-group and S. haematobium infection status determined using parasitological (A) and serological diagnostic techniques (B).

Subgroup centres are represented by the bigger closed (●), or open (○) points, and the distance between these centres is proportional to the level of dissimilarities between subgroups.

Fig 3. Observed prevalences of morbidity by age group, assessed using different diagnostic tools.

Error bars indicate the 95% confidence intervals.

Fig 4. Estimated proportion of morbidity attributable to S. haematobium infection.

(A) Population attributable fraction, (B) Attributable fraction infected.